Long-term outdoor storage of equipment and materials that are subject to damage from corrosion and/or mildew is often necessary in, for example, the construction and mining industries. Also, household and commercial goods are frequently stored outdoors in containers for long periods of time in areas where there is a shortage of warehouse space. The military services must also stockpile equipment and material in outdoor depots for long periods of time. Such storage often occurs in sealed plastic containers. However, regardless of the material of construction, outdoor storage containers are not completely impervious to moisture due principally to leaks around seals and "breathing" as a result of heating/cooling cycles. Consequently, it is usual to seal a solid desiccant material such as silica gel inside an outdoor storage container to adsorb any moisture that might infiltrate through the walls of the container.
Solid desiccants work quite satisfactorily in protecting the contents of outdoor storage containers from the adverse effects of moisture infiltrating the container walls. It was necessary in the prior art, however, to remove solid desiccants from storage containers periodically for "regeneration," i.e., for processing to restore the water-adsorbing capability of the desiccant material. The process of regenerating desiccant material was energy intensive, requiring approximately 2500 Btu to remove a pound of water (or 5815 joules per gram). Furthermore, many manhours were required in the prior art for inspecting, removing, regenerating and reinstalling solid desiccant materials in outdoor storage containers.
A need has long existed for a technique that would enable solid desiccant materials in outdoor storage containers to be automatically regenerated, preferably by passive solar means, without requiring removal of the desiccant materials from the storage containers.